Audible reel signal for motionpicture projectors



y 0, 1949. J. G. JACKSON 2,469,731

AUDIBLE REEL SIGNAL FOR MOTION-PICTURE PRQJECTORS Original Filed Dec. 1, 1943 H I I lNVE-N TOR U. G. JACKSON Patented May 10, 1949 AUDIELE REEL SIGNAL FOR MOTION- PICTURE. PROJECTORS James Gordon Jackson, Vancouver, British lumbia, Canada, assignor of one-half to James Nelson Trumpour, Port Alberni, British Columbia, Canada Original application December 1, 1943, Serial No.

512,491. Divided and this application December 29, 1945,Serial No. 638,114

Claims.

This invention relates to audible reel signals for motion picture projectors and this application is a division of my co-pending application, Serial No. 512,491, filed as of December 1, 1943, which has matured to Patent No. 2,433,908, dated January 6, 1948.

It is necessary that a motion picture projector operator be prewarned that a second projector should be placed in operation upon completion of the reel in the first projector. Audible signals have previously been employed for this purpose but in most cases have involved complicated construction causing a squeal or chatter in oper ation which distracts from the effect of the signal. Furthermore, they have required frequent servicing. The above mentioned disadvantages are overcome by my invention.

It is, therefore, an object of this invention to provide a very simple audible signal means for indicating that the showing of a motion picture reel is about completed.

A further object of this invention is to provide a simple signal which will be brought into operation by the speed of the reel and which will be substantially free from squeal or chatter.

A further object of this invention is to provide an audible signal means employing a minimum of parts.

A still further object of this invention is to provide an audible signal which by reason of its particular simplicity and few parts will avoid frequent servicing.

With these and other objects in view, the invention generally comprises audible signalling means including a pendulum operable by the reel shaft, the motion of said pendulum becoming an accentuated oscillation as the angular velocity of the reel approaches the naturalfrequency of the pendulum and a cooperating sound-producing means intermittently engaged by the swinging pendulum.

The invention will be clearly understood by reference to the following detailed specification taken in conjunction with the accompanying drawings.

In the drawing,

Fig. 1 is a top plan view of the top reel of a projecting machine shown in conjunction with a rotatable rear shutter and illustrating a rotatable drum used in conjunction with a visual signal means of a co-pending application.

Fig. 2 is a front elevation of Fig. 1 illustrating the swingable pendulum associated with the drum for effecting an audible signal.

Fig. 3 is a front elevation similar to Fig. 2

' signal at a predetermined time.

but with the shutterremoved and showing the drum partially in section. V

Fig. 4 is a side elevation of Fig. 3; and

Fig. 5 is a miniature top plan view of the projecting machine illustrating the cooperation between the door of the projector and the audible si nal.

Referring to' the drawings, A indicates the casing of the feeding motion picture reel and 13 indicates a light source, intermittently projected through the film, in combination with the rotatable rear shutter l0 housed within the shutter casing H. The beam is designed to be projected through the opening l2 of the projector. On the reel shaft l3 a drum I4 is mounted which is divided into a plurality of light and dark bands l5 and i6, and may be employed operating in conjunction with the light source B and mirror I! as a visual signal means which is the subject of a co-pending application.

The audible signal means includes a pendulum I8 having a shank l8a and a movable weight 19, said pendulum being eccentrically pivoted at 20 to a disk or collar member 2| connected to and rotatable with the reel shaft. The weight I!) is slidable on the shank I81: and is held in any desired position by friction, or by a set screw, not shown. The pendulum is designed to cooperate with a means for producing a sound One such means for producing sound may takethe form of a chime plate 22. The chime plate (or audible signal member) is positioned on a, chime arm 23 pivota'ble about the point 24 as shown in Fig. 1, said arm being mounted on a suitable bracket 25 attached to the film housing as shown in Fig. 4. A stop 26 (Fig. 1) is provided on bracket 25 for the purpose of automatically setting the chime arm 23 in the correct operating position.

In operation, this device depends upon the fact that as the film becomes used, the angular speed of the reel increases in order that the film may pass the projecting lens at a constant speed. The upper end of the pendulum follows the circle of rotation of the pivot point 29 and said pendulum gently sways back and forth through a small arc until the shaft 13 attains a frequency of rotation equal to the natural frequency of the pendulum. At this point, the pendulum swings freely in a wide arc and strikes the chime signal intermittently over a brief period of time. The upper end of the pendulum follows the path marked F while the lower end moves up and down and at the same time, swings in an arcuate path, the centre line of which is marked G.

3 When the operator has heard the audible signal, he may swing the chime arm 23 member about its pivot point 24 to position the audible signal clear of the swinging pendulunnthus eliminating its continuing: operation. The signal chime thus. removed from the path of the swinging pendulum is automatically repositioned in its oper-. ating position as the door of the film housing is opened to replace the TUHQOHfiJfiImQ operation is best understood by reference to Fig. 5.

The film housing door 21 isopenedand nengag-es the projecting end of the pivoted chime. arm..23'

as at 28 causing the chime arm to swing back to its operating position against stop pin 26. Thus, after a used reel has been replacedi-thesalarmis always set for the correct operation of 'the'signal; The natural frequency of the pendulum is variable with the positioning of the weight: on the. shank, hence the angular velocity of the reel shaft a-t: which the arm.sounds-.can be: varied by varying the position of the-pendulum. weight on the shaft.. It is, therefore, a simple; matter-to use the same signal for more. than onehub size byvarying. the position of the weight. on, the pendulum shank.

From the foregoing it is evident that I have.- provided a simple audible signal for motionpicture reels and; the like operable. by the rotation of the reel. Itemploysaminimum of parts, is freesfrom noise and iseasily adaptable for use in conjunction with varied sizes of reel hubs to produce a signal at s a; predetermined time.

What I. claim as my invention is LAn: audible signal. for. reels of motion. picture; projectors comprising an oscillatory'means operatively connected to. the. reel shaft and a sounds. producing means, said. oscillatory means. being designedcontinuously to oscillate with a v maximum amplitude at a. predetermined reel.

speed to operate the. soundpnoducing means, the

latter being. adjustabl-y mounted and movable:

between an-operati-ve position andan inoperative-position. out of I the. path of theoscillatory means, and'movable'means in connection. with said. projector. movable when. changing a. reel for actuating said.v sound. producing meansinto. an.

operative position.

2. An audiblesignal forreels of motion pic ture projectors. as claimed. in claimlltin whichthe sound producing means is mounted. onan. arm; adjacent one end. thereof, said arm being. piv- 4 otally mounted intermediate its ends on said projector, the opposite end of said arm freely projectlng, said movable means on said projector beingdesigned to. engage. thefreely projecting end of said armto return the latter and; the sound producing means to operative position.

3. An audible signal for reels of motion picture projectors and the like comprising oscillatory meansand asound producing means, said oscillatory means including a free pendulum pivotally connectedand. eccentric to a hub, said hub being operatively, connected to the reel shaft and said pendulum being, caused to oscillate freely with a maximum. amplitude at a predetermined reel speed, said sound producing means being operatively-positio-ned; in; the arc of the freely swinging pendulum substantially at the point of the maximum arcuate motion of said pendulum.

4. audible signal for reels of motion pic ture projectors and the-like comprising a disc mounted on:- and rotatable with thereel shaft, a

free pendulum'pivotedzat its upper endtothe disc. eccen-trically thereof, a weight adjustabl-y mounted on the pendulum adjacent its opposite-- end, said pendulum. oscillatinggently in an arcuate path as the disc rotates, and sound producing means located at .an extremity of the-path. of the free'end of: the. pendulum, said sound. producingmeans' being struckbythe pendulum when: thev latter oscillates freely with-a maximmns-amplitude.

at a predetermined reel-speed,

5. An audible-signal. as claimed v claim- 4 in which. the soundproducing means ismounted on one. end of anarm, said armbeingipivoted-between. the ends: thereof, means for stopping the: arm with the sound. producing means. in its;opera.- tive position, and the oppositewend of the arm beingv engaged by the filmhousing door. when the latter is opened: to.- move. thesound. producing.

means into. position.

JAMES GQRDON. JACKSON.

REFERENCES. GI'IIED 'Ihe. following: references are of record-in the file of this; patent? UNITED STATES PATENTS.

Number Name Date 2,138,648 Stankey Nov-L 29, 1938 2140,22 7. Hemmingsonz.-. Dec... 13,. 1938-1 2,175,938 Fry; Oct. 10,5193?! 

